M000000493

$$\pi=16\arctan\left(\frac{1}{4}\right)-16\arctan\left(\frac{1}{21}\right)-4\arctan\left(\frac{1}{237}\right)+4\arctan\left(\frac{1}{28322}\right)$$

Compact formula	`16[4] - 16[21] - 4[237] + 4[28322]`
Lehmer's measure	3.06297